Preparation and budding growth of whiskers in a homogeneous system

Ca10(PO4)6(OH)2 (HAP) and NH4Al(OH)2CO3·H2O (AACHH) whiskers were prepared by a homogeneous precipitation method based on urea hydrolysis reaction. To clarify the growth process of whiskers in the homogeneous system, XRD and SEM results of the products obtained at different reaction time were investigated in detail. A novel observation about budding growth in preparing both whiskers was described. It was indicated that the growth of whiskers went through three stages, which were oversaturation, nucleation, and budding growth. The growth units of whiskers budded from the surfaces of substrates, which were crystallized flakes for HAP preparation and amorphous spherical nuclei for AACHH preparation. Subsequently, the whiskers grew up accompanying with the disappearing substrates. One-dimensional whiskers with fine morphology and large slenderness ratio were finally obtained. Besides, according to the crystal growth and the interface diffusion theories, the effects of the templates and the budding growth mechanism were discussed.

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► We prepare two kinds of whiskers by homogeneous precipitation method.
► We observe similar budding growth in preparing different whiskers.
► The growth goes through three stages: oversaturation, nucleation, and budding.
► Interface diffusion and hydrogen bonds govern the one-dimensional growth.